1. Field
The following description relates to a semiconductive composition having a volume resistivity of a semiconductive material maintained below a predetermined level while not deteriorating dispersion with a base resin, and a power cable using the same.
2. Description of Related Art
Conventionally, a large amount of carbon black was filled into a semiconductive composition for a power cable to maintain a volume resistivity of a semiconductive material below a predetermined level. For example, Korean Patent No. 10-522196 discloses a semiconductive composition for a high pressure cable, including a base resin and 45 to 70 parts by weight of carbon black. In addition, Korean Patent No. 10-450184 suggests a semiconductive water blocking pellet compound for a power cable, including a base resin and 20 to 50 parts by weight of carbon black. Moreover, Korean Patent No. 10-291668 teaches a semiconductive material for a high pressure cable, including a matrix resin and 40 to 80 parts by weight of carbon black.
As mentioned above, carbon black in a conventional semiconductive material was used with a large amount relative to a base resin, so that, disadvantageously, a power cable may have an increased volume and weight and a poor dispersion between the carbon black and a base resin. Generally, acetylene carbon black with high purity is used as the carbon black. However, acetylene carbon black contains a large amount of impurities, including, for example, ionic impurities, such as calcium, potassium, sodium, magnesium, aluminum, zinc, iron, copper, nichrome, silicon and so on, and other impurities, such as ash, sulfur and so on. These impurities may create a large protrusion in an insulation of a power cable.
Accordingly, there is an urgent need for a semiconductive composition capable of reducing a size of an insulation protrusion that may occur, as well as maintaining a volume resistivity of a semiconductive material below a predetermined level while not deteriorating the dispersion with a base resin.